I like picking up different things when I go out with my dog for walks. One of my favorite things in the fall is finding & comparing different kinds of acorns. I've read there are more than 400 different kinds of oak trees, and I suppose there are almost as many different kinds of acorns. These two big acorns are easy: they're from a bur oak. I used to collect dozens of these for a co-worker to take home to his daughters, and they would make little "rasta people" from them. I still pick them up out of habit and because they're interesting to look at. Lately my dog Kiera has taken to circling and re-circling the bur oaks at a nearby park on the off chance she'll scare up a squirrel. They're up in the trees, alright, but usually they're smart enough to stay up there. They like to drop (or throw?) their half-eaten acorns and woe to any unfortunate dog-moms (me) standing below. Those acorns are deadly little missiles.
The little acorn may be from a shumard oak, but it could be from a nuttall oak. Next time after things dry out a bit from our recent heavy rain I'll pick up some leaves to help identify it.